1. Technical Field
This application relates to a rotational thrombectomy wire for clearing thrombus from native vessels.
2. Background of Related Art
There have been various attempts to break up clots and other obstructing material in the graft. One approach is through injection of thrombolytic agents such as urokinase or streptokinase. These agents, however, are expensive, require lengthier hospital procedures and create risks of drug toxicity and bleeding complications as the clots are broken.
Other approaches to breaking up clots involve mechanical thrombectomy devices. For example, U.S. Pat. No. 5,766,191 discloses a cage or basket composed of six memory wires that expand to press against the inner lumen to conform to the size and shape of the lumen. This multiple wire device is expensive and can be traumatic to the graft, possibly causing damage, since as the basket rotates, the graft is contacted multiple times by the spinning wires. Other risks associated with the basket include the possibility of catching onto the graft itself and tearing the graft as well as catching and tearing the suture at the anastomotic site. Additionally, the basket can become filled with a clot which would then require time consuming withdrawal of the basket, cleaning the basket and reinserting it into the lumen. This device could be traumatic if used in the vessel, could denude endothelium, create vessel spasms and has the potential for basket and drive shaft fracture.
U.S. Pat. No. 6,090,118, incorporated herein by reference in its entirety, discloses a wire rotated to create a standing wave to break-up or macerate thrombus. The single wire is less traumatic than the aforedescribed basket device since it minimizes contact with the graft wall while still effectively mechanically removing thrombotic material.
U.S. Pat. No. 7,645,261, the entire contents of which are incorporated herein by reference, discloses a thrombectomy device having a double balloon structure. This device advantageously reduces the number of individual catheters required to perform the thrombectomy procedure and reduces the number of surgical steps, thus simplifying the procedure and reducing operating costs.
U.S. Pat. No. 7,037,316, the entire contents of which is incorporated herein by reference discloses another example of a rotational thrombectomy wire for breaking up clots in grafts. The thrombectomy wire has a sinuous shape at its distal end and is contained within a sheath in a substantially straight non-deployed position. When the sheath is retracted, the distal portion of the wire is exposed to enable the wire to return to its non-linear sinuous configuration. The wire is composed of two stainless steel wires wound side by side with an elastomeric tip at the distalmost end. Actuation of the motor causes rotational movement of the wire, creating a wave pattern, to macerate thrombus. Thus, it provides the additional advantages of increased reliability and consistency in creating the wave pattern since the wave pattern created by the standing wave of the '118 patent will depend more on the rotational speed and the stiffness of the wire. Additionally, the sinuous configuration enables creation of a wave pattern at a lower rotational speed.
Although the sinuous wire of the '316 patent is effective in proper clinical use to macerate thrombus in dialysis grafts, it is not best suited for use in native vessels. US patent publication no. 2006/0106407, the entire contents of which are incorporated herein by reference, discloses a thrombectomy wire better suited for use in native vessels, and can also be used for deep vein thrombosis and pulmonary embolisms.
In certain thrombectomy procedures, such as in neurovascular or pulmonary procedures, during wire rotation, broken plaque particles which are dislodged can travel through the vascular system. If these particles are too large, then they can create risks for the patient as they travel downstream through the vessels, causing clots which can result in stroke or in certain instances death of the patient. It would be advantageous to reduce these risks in these procedures.